<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* css 的内嵌式写法 */
    body {
      color: red;
    }
  </style>
</head>
<body>
</body>
</html>
<script>
// 英文
  // block -  代码块

{
  var num = 123;
  var num2 = 456;
  alert(num + num2);
}
</script>